Wisdom Teeth Should they be removed?

Wisdom teeth, also known as third molars, are the teeth located furthest back in the jaws. They are the last ones to emerge (erupt) into the mouth and become visible. These teeth vary most in the timing of development, crown and root structure, and position.

Figure 4: X-ray of a lower jaw requiring major surgery because of a large lesion (white arrows) associated with an impacted wisdom tooth (red arrow) and causing impaction of a second molar tooth (green arrow).

In some people, these teeth erupt completely and are functional (Figure 1a). However, in most people wisdom teeth are either partially erupted (Figure 1b), or fully impacted within the jaw bones (Figure 2). In these situations, the teeth do not work properly and may need to be removed.

The position of wisdom teeth is affected by the size of the tooth in relation to the jaw, and how they develop within the jaws. A problem or lesion in the jaw can also determine the position of wisdom teeth (Figure 3).

Emerging and erupted wisdom teeth

Erupted wisdom teeth are more likely to develop plaque and cavities. They are harder to brush and floss properly. The lower jaw can get in the way when cleaning wisdom teeth on the upper jaw. The cheek muscles can interfere when cleaning the lower wisdom teeth. Often, when these teeth erupt partially, a flap of unattached gum tissue remains. This acts as a trap where food debris and plaque can collect. Debris that builds under the soft tissue flap may inflame the gums. It can also infect the area, causing pain, trouble opening the mouth, bad taste and odour. Molars partly covered by soft tissue are 22 to 34 times more likely to develop disease than those at other stages of eruption.

In some cases, the position of the erupted wisdom teeth creates a tight contact area with the next molar.
This prevents proper flossing and cleansing which leads to cavities. Restorative dental treatment on both molars will then be needed. The teeth may even be lost.

Sometimes wisdom teeth have been removed to prevent crowding of the front teeth (incisors), particularly in the lower jaw. However, most studies reviewing this risk found little or no effect. As a result, the decision to remove wisdom teeth should be based on other concerns.

Teeth that have not emerged

Wisdom teeth are the molars most often impacted (unerupted). This occurs more often in the upper jaw than the lower.

When wisdom teeth remain impacted in the jaw, they are at risk for other problems. Molars completely covered by soft tissue or bone tissue have about equal risk of developing disease as those that are partly covered. In particular, the follicle surrounding an unerupted tooth can sometimes grow, forming a cystic lesion. The most common type associated with unerupted wisdom teeth is known as a dentigerous cyst. It happens more often in the lower jaw. Other less common, but more aggressive, lesions are also linked with impacted wisdom teeth. One type often requires surgery to avoid significant deformities and fractures (Figure 4).

Sometimes, impacted wisdom teeth must be removed because of specific medical conditions or to prevent the management of future eruption.

In these cases, the risk of keeping the teeth outweighs the risk of possible complications from removal, even if teeth are not causing symptoms.

Other, less common reasons for removing unerupted wisdom teeth include:

transplanting the molars into another site

removing molars so they do not interfere with eruption of the second molars

if the tooth is in the way of repairing a jaw fracture

avoiding confusion with diagnosing jaw joint (TMJ) or muscle problems if there is unusual pain in the area.

Risks of surgery

As with any type of surgery, specific risks are associated with removing wisdom teeth. The risks often involve neighbouring nerves, vessels, sinuses, glands and muscles.

Nerve injury resulting in temporary or permanent loss of sensation is associated with two main lower jaw nerves. However, this happens in less than one per cent of surgeries. Other possible complications include:

‘dry socket’ or loss of the blood clot that forms when the tooth is removed

infection

‘secondary hemorrhage’ or excessive bleeding.

After surgery, there may be pain, trouble opening the mouth, swelling and tiredness. About half of patients have these concerns during the first few days. Damage to the next tooth and tissues surrounding and supporting it, or developing a deep pocket next to the second molar, are rare. (Again, this generally involves less than one per cent of cases.) Fractures to the jaw occur, but very rarely. An oro-antral fistula, where an opening develops between the mouth and the maxillary sinus above, is also very rare.

Removing wisdom teeth that have extensive cavities, severe gum issues, disease or infection is generally a clear decision. The choice is less simple in the case of wisdom teeth that have no symptoms. Much literature suggests removing these teeth, while some says there is no need.

Your dental care provider should inform you of the pros and cons of keeping or removing wisdom teeth Monitoring the situation and using x-rays will help ensure that un-erupted wisdom teeth are doing well in their growth and eruption process.

Inform yourself of the risks and possible complications of retaining or removing the wisdom teeth. Ask about the follow-up process in each scenario. The decision to remove or retain wisdom teeth should be mutual; made by a well-informed patient and a skilled dental care provider.